Suggest Remedy For Itchy Patches/rashes On Skin

Hi, I am female, 41, 5 ft 6 and approx 8 stone 9 with no medical conditions. For the past few weeks I have been getting hot itchy patches on the skin (face, wrists, ankles today) which almost feels numb whilst itchy and I get a crescent shaped rash. This will disappear after a period of time, ans skin returns to normal. Any ideas